Mattress lift



FIG. 1 is perspective view of a mattress lift showing my new design;

FIG. 2 is another perspective view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a rear elevation view thereof;

FIG. 5 is a side elevation view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines, which define the bounds of the claimed design, form no part thereof. 

The ornamental design for a mattress lift, as shown and described. 